erlang-mooc-exercise-1.9

first.erl

-module(first).

-export([double/1, mult/2, area/3, square/1, treble/1]).

mult(X, Y) ->
  X * Y.

double(X) ->
  mult(2, X).

treble(X) ->
  mult(3, X).

area(A, B, C) ->
  S = (A + B + C) / 2,
  math:sqrt(S * (S - A) * (S - B) * (S - C)).

square(X) ->
  mult(X, X).

second.erl

-module(second).

-export([hypotenuse/2, perimeter/2, area/2]).

hypotenuse(A, B) ->
  ABS = first:square(A) + first:square(B),
  math:sqrt(ABS).

perimeter(A, B) ->
  A + B + hypotenuse(A, B).

area(A, B) ->
  A * B / 2.

Great job!!